Regulus/Neville
Not many people here would call him Professor, not unless they had to, and even then he was pretty sure that they didn't like it. However when he heard the title, there was no trace of sarcasm. He turned and regarded the man approaching him.
Longbottom was someone he didn't understand. He came from a long line, good pedigree, related to the Black family and yet he acted like he was... nothing. Regulus didn't understand how that was even possible.
"Good afternoon," he said in greeting. "You're more than welcome to join me." He wasn't sure what there was to join in this garden, but he bit his tongue. Sirius would have to build him a statue for how nice he was being. "Are you enjoying the festivities?"